 Hello everybody and welcome to the first video of the free online version of the Fusion Research Lecture. This is the outline I described in detail in the last video in the introduction video. And today we start with chapter one, the entitled Fusion Research. And we give a bit of a historical, a bit of an historical overview. And very first, as a very first date probably we should start in 1919, where the first nuclear fusion reaction in the lab was performed. So 1919 we had the first nuclear fusion reaction, the lab performed by Ernest Rutherford, one of the greatest experimental physicists. And what he had done, what he had done was shooting an alpha particle onto nitrogen. And then he observed that this changed into a rare isotope of oxygen and a proton. Only one year later, in 1920, the mass defect was for the first time measured. So the mass defect, the mass defect of the helium, the nucleus relative to four hydrogen, nuclei, so four protons, was for the first time measured in the lab. And this was done by Francis William Aston. And it was the same year that Eddington suggested that the conversion of hydrogen into helium might be responsible for the sun's energy source. So in the very same year, Eddington suggested that the conversion of hydrogen to helium is responsible for the sun's, or might be responsible for the sun's energy source. And this is the quote, the full quote now, which I already mentioned in the introduction, which Sir Arthur Eddington made in 1920 at a conference. And I'd like to quickly read it as it is a very important quote. A star is drawing on some vast reservoir of energy by means unknown to us. This reservoir can scarcely be other than the subatomic energy, which it is known exists abundantly in all matter. We sometimes dream that man will one day learn how to release it and use it for his service. So he kind of predicted the peaceful use of fusion energy in this quote a hundred years ago. Quite remarkable, I think. Eddington was also known as being one of the greatest theoretician at his time. Now it took a while before the sun's energy source was actually explained, and that was in 1938. So 1938, the sun's energy source explained. Energy source explained. That was by Beta and Weizsäcker. By Beta and Weizsäcker. And we will come to that in detail in one of the next videos. And afterward, where two fusion research really started to kick off, and at first it was all on pinches. And we will talk about pinches in a few slides. So it was all about research on pinches. Okay, but before we come to the peaceful use of fusion energy, there was unfortunately also the not-so-peaceful use, and here you see a picture of the first hydrogen bomb. So that was in 1952. There was a hydrogen bomb called Ivy Mike. Ivy Mike. And since that time, the expression thermonuclear reaction, thermonuclear reaction, is somehow related to the non-peaceful use of fusion energy and has a bad reputation. And this is why nowadays we rather talk about fusion than we talk about the peaceful use of the thermonuclear reaction. So this has more of a positive reputation, I would say. Okay, so in the 1950s, the toroidal confinement concepts appeared as the next step toroidal confinement concepts. And we will talk about them a lot, about these concepts a lot in this lecture, toroidal confinement concepts. And these were mostly, of course, the Stellarator and the Tokamak. Stellarator and Tokamak. In 1955, the first International United Nations Conference on the Peaceful Use of Atomic Energy happened because the labs throughout the world realized that they... sorry, that was the first time the scientists from the different labs started realizing that they all have kind of similar problems. So it was an important date. So this was the first United Nations organized conference on the peaceful use of atomic energy. Atomic energy. And it had the nice name Atoms for Peace. Atoms for Peace. And it took place in Geneva. And another very important conference is... took place three years later, 1958. That was the second Atoms for Peace conference. The second Atoms for Peace conference, which also took place in Geneva. And that was important because in that year and after that conference it was decided to declassify fusion research. And that is quite remarkable because the Cold War was kind of peaking there and still the countries decided to declassify fusion research. You probably know one of the famous misunderstandings about fusion is that it is always 20 years away. And this kind of misunderstanding or misconception of fusion started basically already at the first International Fusion Conference in 1955 when Homi J. Baba, the head of the conference, gave an official statement to the press. Homi J. Baba is also known as being the father of the Indian fusion and Indian nuclear program in general. And I'd like to quickly read that quote. It reads, it is well known that atomic energy can be obtained within the entire fusion process as in the H-bomb. The technical problems are formidable, but one should remember that it is not yet 15 years since atomic energy was released in an atomic pile for the first time by Ferney. I venture to predict that a method will be found for liberating fusion energy in a controlled manner within the next two decades. When that happens, the energy problems of the world which truly has been solved forever for the fuel will be as plentiful as the heavy hydrogen in the oceans. The fact that he said in 20 years we will have fusion energy. That statement was not supported by all of his colleagues, but however it was made to the press and people expected that. In addition, from fission, people knew that it only took 10 years from the first fission bomb to the first fission reactor, so there were also some expectations into that direction. It turned out however that fusion is a bit more complicated as we will see throughout this lecture. Coming back to the historical overview, a very important first concept were the pinches. It is important to understand them, to understand some very basic concepts and limitations, and this is why we mentioned them here. The pinches remain of the general idea that we have heating by compression. We need high temperatures for fusion, and we cheat that by compression. As an example, we will start with a linear Z-pinch. Linear Z-pinch. Now on the linear Z-pinch what you start with, two electrodes. So let's try to draw one electrode, and another electrode, and another electrode. We have a strong voltage between them, so this is for example positively biased. Here we have negative voltage. Now having a strong voltage that's eventually, if the voltage is high enough, in the current flowing between these two electrodes. So for example something like this, these are supposed to be the current flowing between them, and J, so this is the current J here, and this is how the pinch basically starts. So first of all we have the current J. Now from MPS law, we know that the current generates a magnetic field. So MPS law tells us that there is an estymuthal magnetic field created by that, and for that magnetic field, we use the color blue and it will look something like this. That's an estymuthal field, as I have written down there. And we know that this magnetic field, for example if we have two wires, where the current flows parallel, or two wires being parallel to each other, where the current flows into the same direction, we know from the Laurentian force that these two wires attract each other. This is kind of a famous high school experiment, so we know from this kind of experiment that due to the Laurentian force the wires attract each other, so there is an inwards directed force here. So we have the Laurentian force, which creates an inwards directed force, and if we go back to our picture here above, again we have the current, and due to the magnetic field, pushes the current together, so it leads to a first kind of compression, right? So this is remember the magnetic field, this leads to an inwards directed force, and this increases, so as a third, sorry, as a third time step, the compression might be even higher, so this might be even closer together, for example something like this, still the magnetic field into compression, and the idea that eventually the compression will be so high that we achieve ignition, so that the pressure for fusion is fulfilled, required for fusion. However, there are a few problems with this concept, problems, one concept is, one problem is that since we have a strong current flowing between these two electrodes, we will have erosion at the electrodes, so the electrodes will erode, and in addition, the plasma will become rapidly unstable, so the plasma rapidly becomes unstable, becomes unstable, it kinks, what does that mean? Of course, the compression is not homogeneous, as one would probably hope for, but if you draw a plasma column, for example we might have an initial perturbation, which leads to some compression already here, then further away down the column, we have the further initial compression, which leads to something like this, and the problem is that since at these points where we have some initial compressions or perturbations leading to compressions already, the higher magnetic field at this area leads to further compression, thus the plasma becomes unstable, quickly. Now, a different concept, another pinch, is the so-called theta pinch, theta pinch, also with the letter theta pinch, if you look for that. Now, what we have here is, we start first with a plasma column, so let's try to draw a plasma column, for example, an extended plasma column, something like this, make it a big thicker, so this is our plasma column, let's label that, so this is a plasma column, and now we start with a cylindrical single-turn coil, so around the plasma column, we will now try to draw some kind of cylindrical coil, quite not too bad, which is extended into this direction, something like that, it goes like here, and here, and as I said, it's extended into that direction, now it looks like this, for example, and so, as I said, this is a cylindrical single-turn coil, and we connect that to a circuit, to a plasma column, we connect that to a circuit, to a circuit, where we have a capacitor bank included, something like that, and if we close the switch, there will be a fast-rising azimuthal current flowing in the coil, so there will be a fast-rising azimuthal current, so flowing here along the coil, so this will be the coil current, and we know that from MPS law, the current creates an fast-rising axial magnetic field, axial magnetic field pointing into this direction, which changes fastly in time, so this is BZ, and then from Faraday's law, we know that this in turn, as it is changing in time, creates an azimuthal current in the plasma, J theta, which flows in the opposite direction in the coil current, so it flows into this direction, so this is supposed to be the plasma current, the induced plasma current, induced plasma current, and this via the Laurentian force now leads again to compression, so you can test it on your own, using the right hand roll, then you will see that this leads to compression. Now what is the problem with that? The problem with that concept are the end losses, because we have the magnetic field extended along the plasma column and along the magnetic field, the charges can move freely, so end losses are a big problem here. It is also MHD unstable, however, instabilities are not such a big concern as in the linear Z-pinch. Now third-pinch concept, which was very famous, is the two-royal-pinch. Two-royal-pinch, as we picked on the left-hand side, it works via the transformer principle, so we have the transformer, transformer principle, so we have a primary winding, a primary winding, a primary winding on the left side here, you see the coils, right? And then the plasma is the secondary winding here, where the current is induced, creating a magnetic field. So the plasma is the secondary winding, plasma is the secondary winding. And the picture on the left-hand side, I took that from a reactor patent, a patent for a reactor from the UK, from 1946, which was from Thompson and Blackman. Of course, the reactor did not work because it was based on wrong physical principles, but just to let you know that this was the first reactor patent. The problems with that is similar to the other two-pinch concepts, that we had rapidly growing instabilities, rapidly growing instabilities. And this is illustrated in the next slide, where we can see on the left-hand side a few photographers from the linear Z-pinch. So in the very first column, you see photographers from the top, these are subsequent images in time, this is from the top, this is taken from these are side views. And you see how at first we have a nice plasma column, a nice plasma column which then compresses, so it becomes thinner, smaller, and diameters, everything looks very nicely, but after, let's say, two microseconds roughly, so you see the time indicated here after two microseconds, you see how everything starts to become unstable and the confinement is basically lost and the plasma hits the wall, and this happens long before fusion conditions are achieved. The same is true for the toe-royal pinch, here you see on the right-hand side two photographers where the plasma was inside of the transparent tube, at first everything looked very nicely, very homogeneous plasma, but only after a few microseconds, here you can see how the plasma kings to the side and everything becomes unstable and confinement is basically lost. Now this is of course not the end of the story and in the next video we will see how these limitations will overcome, but for this video the major message is basically that all pinches are subject to MHD instabilities, are subject to instabilities in general, all pinches are subject to instabilities, instabilities, so this is the white topic of magneto-hydrodynamic instabilities also and we will talk about that a bit later, when we talk about parameter limits we will touch that topic again, but as I said the major message here, all pinches are subject to MHD instabilities therefore they are not a candidate for fusion vector. The solution for that we will discuss in the next video. See you in the next video.